Why is AVOD a choice?

Either...
a) Corporate policy, e.g. It's too expensive for AC's nickel and diming to turn it on.
b) Some absurd government regulation prohibits it.

By changing her mind, the FA just admitted that it is something he/she can control, but for 2 hours, he/she CHOSE NOT to. That just makes him/her look bad and lazy, irrespective of the truth. If AVOD is not turned on as a policy, then just say so.

By the way, I was on this flight last week, too, and it was on.